Syria's Readiness for Attack in Question

O'Connor believes the easiest way to do that would be to send a barrage of missiles aimed at the radar sites. "Such a strike would represent a comparatively low-cost and low-risk method of greatly reducing the threat posed by the network," he told ABC News.

"The Syrian IADS (integrated air defense system) is not capable of defeating a large-scale attack by a modern air arm. The overreliance on aging technology, technology often encountered and exploited by Western air arms, puts the overall network at significant risk," he said.

Syria has also tried upgrading its aging Soviet systems by integrating newer Chinese radars and sensors, but O'Connor says it remains to be seen how well they mesh.

Cordesman says the system has other vulnerabilities. "They also have aging surface-to-air missiles (SAM) that have been only partially upgraded and are vulnerable to jamming and other electronic countermeasures, as well as antiradiation missiles," he wrote.

Has the War Taken a Toll on the Syrian Air Defenses?

On this point experts remain divided, largely because it's very difficult to tell from afar.
Pieter Wezeman, who tracks arms shipments at the Stockholm International Peace Research Institute (SIPRI), says that Assad began stocking up on modern defense systems in around 2010 and Russia has continued to deliver components throughout the conflict. But he also points to reports that rebel forces have been able to capture military bases where some systems were stored, though it's unclear if those systems were old or outdated.

"On the basis of that I would expect there to be major gaps in the Syrian air defense system," he told ABC News by email.

O'Connor disagreed.

"Current operations by anti-government forces have had little impact on the overall network," he said, noting that the bulk of surface-to-air systems remain in Assad-controlled areas.

He said crew readiness probably wouldn't be an issue either because those groups haven't played much of a role in the conflict thus far. The rebels, of course, have no planes to defend against.

Cordesman pointed out in May that the fact that Israel was able to hit targets inside Syria may be a sign of how the country's air defenses have degraded. But he also cautioned, "At the same time, this does not mean that Syria could not put up a defense or that the U.S. could simply rely on a few strikes or threats to either destroy Syria's air defense or intimidate it into complying with U.S. demands."

It's unclear how far into Syria Israeli planes had to travel to conduct the bombing, or if they did at all, and how much effort Syria took to stop them, knowing it was only a limited attack. Some believe Israel may have lobbed the bombs over the border, rather than entering Syrian airspace and risking being shot down.